1. Field of the Invention
The present invention relates to the detection of microorganisms in a fluid sample such as, for example, body fluids. More particularly, the present invention relates to a culture bottle assembly wherein a liquid nutrient medium is provided in combination with a solid medium and wherein a fluid sample is incubated in the liquid nutrient medium which is then used to inoculate the solid medium and to continue the growth of organisms which are initially grown in the liquid nutrient medium.
2. Prior Art
The detection of microorganisms in body fluids, particularly bacteria in blood, requires that a sample of the fluid be used to inoculate a liquid nutrient medium. Subsequently, the liquid medium is in turn used to inoculate a solid medium to continue the growth of the organisms and to make them visible to the naked eye as colonies.
Normal monophasic systems consist of a liquid medium in a culture bottle or vial which is inoculated with a sample of the fluid and is then incubated for a desired period of time (24-48 hours). After that, a sample is withdrawn from the bottle and is used to inoculate a solid nutrient medium (agar in a Petri dish).
This procedure is laborious, sometimes hazardous and includes the risk of contamination with microorganisms from the environment. Therefore detection systems have been developed in which liquid and solid culture media are combined in the same container. Such systems avoid the troublesome and sometimes hazardous transfer of the liquid culture to the solid culture medium. U.S. Pat. No. 2,992,974 to Belcove et al, for example, describes a biological testing device in which a solid medium is restrained in the top portion of a rectangular culture bottle while a liquid nutrient medium is provided in the lower most portion of the bottle. U.S. Pat. No. 3,589,983 to Holderith et al describes a culture bottle which is designed to hold a solid agar nutrient material at a location along the axial centerline of a bottle. The bottle also houses a liuid nutrient broth which may be separated from the solid agar by positioning the bottle on its side.
The above described prior art devices which combine a liquid nutrient medium in a single container with a solid medium have a major disadvantage in that the culture assembly must be positioned in a certain manner prior to contacting the solid medium with the precultured liquid medium. The above described prior art devices for separating solid and liquid culture media are complicated and facilitate separation of the liquid media and the solid media only during incubation, but not during transport.
U.S. Pat. No. 4,308,347 to Forrer et al describes a device for detection of microorganisms in a fluid sample which includes a first container holding a liquid nutrient medium and a second container containing one or more solid nutrient medium. The containers are detachably connected so that the media can be brought into contact when desired. The device described in the Forrer Patent is complicated and requires several manipulative steps to bring the precultured liquid media into contact with the solid medium.
The above disadvantages of the prior art are overcome in accordance with the present invention which provides a simple culture bottle assembly which contains a liquid media and one or more solid nutrient media in a single container with easily effected means for bringing the precultured liquid media into contact with the solid media when desired.